linux-user/flatload.c

   1 /****************************************************************************/
   2 /*
   3  *  QEMU bFLT binary loader.  Based on linux/fs/binfmt_flat.c
   4  *
   5  *  This program is free software; you can redistribute it and/or modify
   6  *  it under the terms of the GNU General Public License as published by
   7  *  the Free Software Foundation; either version 2 of the License, or
   8  *  (at your option) any later version.
   9  *
  10  *  This program is distributed in the hope that it will be useful,
  11  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  *  GNU General Public License for more details.
  14  *
  15  *  You should have received a copy of the GNU General Public License
  16  *  along with this program; if not, write to the Free Software
  17  *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  18  *
  19  *      Copyright (C) 2006 CodeSourcery.
  20  *      Copyright (C) 2000-2003 David McCullough <davidm@snapgear.com>
  21  *      Copyright (C) 2002 Greg Ungerer <gerg@snapgear.com>
  22  *      Copyright (C) 2002 SnapGear, by Paul Dale <pauli@snapgear.com>
  23  *      Copyright (C) 2000, 2001 Lineo, by David McCullough <davidm@lineo.com>
  24  *  based heavily on:
  25  *
  26  *  linux/fs/binfmt_aout.c:
  27  *      Copyright (C) 1991, 1992, 1996  Linus Torvalds
  28  *  linux/fs/binfmt_flat.c for 2.0 kernel
  29  *          Copyright (C) 1998  Kenneth Albanowski <kjahds@kjahds.com>
  30  *      JAN/99 -- coded full program relocation (gerg@snapgear.com)
  31  */
  32
  33 /* ??? ZFLAT and shared library support is currently disabled.  */
  34
  35 /****************************************************************************/
  36
  37 #include <stdio.h>
  38 #include <stdlib.h>
  39 #include <errno.h>
  40 #include <sys/mman.h>
  41 #include <unistd.h>
  42
  43 #include "qemu.h"
  44 #include "flat.h"
  45
  46 //#define DEBUG
  47
  48 #ifdef DEBUG
  49 #define DBG_FLT(a...)   printf(a)
  50 #else
  51 #define DBG_FLT(a...)
  52 #endif
  53
  54 #define flat_reloc_valid(reloc, size)             ((reloc) <= (size))
  55 #define flat_old_ram_flag(flag)                   (flag)
  56 #ifdef TARGET_WORDS_BIGENDIAN
  57 #define flat_get_relocate_addr(relval)            (relval)
  58 #else
  59 #define flat_get_relocate_addr(relval)            bswap32(relval)
  60 #endif
  61
  62 #define RELOC_FAILED 0xff00ff01         /* Relocation incorrect somewhere */
  63 #define UNLOADED_LIB 0x7ff000ff         /* Placeholder for unused library */
  64
  65 struct lib_info {
  66     target_ulong start_code;    /* Start of text segment */
  67     target_ulong start_data;    /* Start of data segment */
  68     target_ulong end_data;      /* Start of bss section */
  69     target_ulong start_brk;     /* End of data segment */
  70     target_ulong text_len;      /* Length of text segment */
  71     target_ulong entry;         /* Start address for this module */
  72     target_ulong build_date;    /* When this one was compiled */
  73     short loaded;               /* Has this library been loaded? */
  74 };
  75
  76 #ifdef CONFIG_BINFMT_SHARED_FLAT
  77 static int load_flat_shared_library(int id, struct lib_info *p);
  78 #endif
  79
  80 struct linux_binprm;
  81
  82 #define ntohl(x) be32_to_cpu(x)
  83
  84 /****************************************************************************/
  85 /*
  86  * create_flat_tables() parses the env- and arg-strings in new user
  87  * memory and creates the pointer tables from them, and puts their
  88  * addresses on the "stack", returning the new stack pointer value.
  89  */
  90
  91 /* Push a block of strings onto the guest stack.  */
  92 static target_ulong copy_strings(target_ulong p, int n, char **s)
  93 {
  94     int len;
  95
  96     while (n-- > 0) {
  97         len = strlen(s[n]) + 1;
  98         p -= len;
  99         memcpy_to_target(p, s[n], len);
 100     }
 101
 102     return p;
 103 }
 104
 105 int target_pread(int fd, target_ulong ptr, target_ulong len,
 106                  target_ulong offset)
 107 {
 108     void *buf;
 109     int ret;
 110
 111     buf = lock_user(ptr, len, 0);
 112     ret = pread(fd, buf, len, offset);
 113     unlock_user(buf, ptr, len);
 114     return ret;
 115 }
 116 /****************************************************************************/
 117
 118 #ifdef CONFIG_BINFMT_ZFLAT
 119
 120 #include <linux/zlib.h>
 121
 122 #define LBUFSIZE        4000
 123
 124 /* gzip flag byte */
 125 #define ASCII_FLAG   0x01 /* bit 0 set: file probably ASCII text */
 126 #define CONTINUATION 0x02 /* bit 1 set: continuation of multi-part gzip file */
 127 #define EXTRA_FIELD  0x04 /* bit 2 set: extra field present */
 128 #define ORIG_NAME    0x08 /* bit 3 set: original file name present */
 129 #define COMMENT      0x10 /* bit 4 set: file comment present */
 130 #define ENCRYPTED    0x20 /* bit 5 set: file is encrypted */
 131 #define RESERVED     0xC0 /* bit 6,7:   reserved */
 132
 133 static int decompress_exec(
 134         struct linux_binprm *bprm,
 135         unsigned long offset,
 136         char *dst,
 137         long len,
 138         int fd)
 139 {
 140         unsigned char *buf;
 141         z_stream strm;
 142         loff_t fpos;
 143         int ret, retval;
 144
 145         DBG_FLT("decompress_exec(offset=%x,buf=%x,len=%x)\n",(int)offset, (int)dst, (int)len);
 146
 147         memset(&strm, 0, sizeof(strm));
 148         strm.workspace = kmalloc(zlib_inflate_workspacesize(), GFP_KERNEL);
 149         if (strm.workspace == NULL) {
 150                 DBG_FLT("binfmt_flat: no memory for decompress workspace\n");
 151                 return -ENOMEM;
 152         }
 153         buf = kmalloc(LBUFSIZE, GFP_KERNEL);
 154         if (buf == NULL) {
 155                 DBG_FLT("binfmt_flat: no memory for read buffer\n");
 156                 retval = -ENOMEM;
 157                 goto out_free;
 158         }
 159
 160         /* Read in first chunk of data and parse gzip header. */
 161         fpos = offset;
 162         ret = bprm->file->f_op->read(bprm->file, buf, LBUFSIZE, &fpos);
 163
 164         strm.next_in = buf;
 165         strm.avail_in = ret;
 166         strm.total_in = 0;
 167
 168         retval = -ENOEXEC;
 169
 170         /* Check minimum size -- gzip header */
 171         if (ret < 10) {
 172                 DBG_FLT("binfmt_flat: file too small?\n");
 173                 goto out_free_buf;
 174         }
 175
 176         /* Check gzip magic number */
 177         if ((buf[0] != 037) || ((buf[1] != 0213) && (buf[1] != 0236))) {
 178                 DBG_FLT("binfmt_flat: unknown compression magic?\n");
 179                 goto out_free_buf;
 180         }
 181
 182         /* Check gzip method */
 183         if (buf[2] != 8) {
 184                 DBG_FLT("binfmt_flat: unknown compression method?\n");
 185                 goto out_free_buf;
 186         }
 187         /* Check gzip flags */
 188         if ((buf[3] & ENCRYPTED) || (buf[3] & CONTINUATION) ||
 189             (buf[3] & RESERVED)) {
 190                 DBG_FLT("binfmt_flat: unknown flags?\n");
 191                 goto out_free_buf;
 192         }
 193
 194         ret = 10;
 195         if (buf[3] & EXTRA_FIELD) {
 196                 ret += 2 + buf[10] + (buf[11] << 8);
 197                 if (unlikely(LBUFSIZE == ret)) {
 198                         DBG_FLT("binfmt_flat: buffer overflow (EXTRA)?\n");
 199                         goto out_free_buf;
 200                 }
 201         }
 202         if (buf[3] & ORIG_NAME) {
 203                 for (; ret < LBUFSIZE && (buf[ret] != 0); ret++)
 204                         ;
 205                 if (unlikely(LBUFSIZE == ret)) {
 206                         DBG_FLT("binfmt_flat: buffer overflow (ORIG_NAME)?\n");
 207                         goto out_free_buf;
 208                 }
 209         }
 210         if (buf[3] & COMMENT) {
 211                 for (;  ret < LBUFSIZE && (buf[ret] != 0); ret++)
 212                         ;
 213                 if (unlikely(LBUFSIZE == ret)) {
 214                         DBG_FLT("binfmt_flat: buffer overflow (COMMENT)?\n");
 215                         goto out_free_buf;
 216                 }
 217         }
 218
 219         strm.next_in += ret;
 220         strm.avail_in -= ret;
 221
 222         strm.next_out = dst;
 223         strm.avail_out = len;
 224         strm.total_out = 0;
 225
 226         if (zlib_inflateInit2(&strm, -MAX_WBITS) != Z_OK) {
 227                 DBG_FLT("binfmt_flat: zlib init failed?\n");
 228                 goto out_free_buf;
 229         }
 230
 231         while ((ret = zlib_inflate(&strm, Z_NO_FLUSH)) == Z_OK) {
 232                 ret = bprm->file->f_op->read(bprm->file, buf, LBUFSIZE, &fpos);
 233                 if (ret <= 0)
 234                         break;
 235                 if (ret >= (unsigned long) -4096)
 236                         break;
 237                 len -= ret;
 238
 239                 strm.next_in = buf;
 240                 strm.avail_in = ret;
 241                 strm.total_in = 0;
 242         }
 243
 244         if (ret < 0) {
 245                 DBG_FLT("binfmt_flat: decompression failed (%d), %s\n",
 246                         ret, strm.msg);
 247                 goto out_zlib;
 248         }
 249
 250         retval = 0;
 251 out_zlib:
 252         zlib_inflateEnd(&strm);
 253 out_free_buf:
 254         kfree(buf);
 255 out_free:
 256         kfree(strm.workspace);
 257 out:
 258         return retval;
 259 }
 260
 261 #endif /* CONFIG_BINFMT_ZFLAT */
 262
 263 /****************************************************************************/
 264
 265 static target_ulong
 266 calc_reloc(target_ulong r, struct lib_info *p, int curid, int internalp)
 267 {
 268     target_ulong addr;
 269     int id;
 270     target_ulong start_brk;
 271     target_ulong start_data;
 272     target_ulong text_len;
 273     target_ulong start_code;
 274
 275 #ifdef CONFIG_BINFMT_SHARED_FLAT
 276 #error needs checking
 277     if (r == 0)
 278         id = curid;     /* Relocs of 0 are always self referring */
 279     else {
 280         id = (r >> 24) & 0xff;  /* Find ID for this reloc */
 281         r &= 0x00ffffff;        /* Trim ID off here */
 282     }
 283     if (id >= MAX_SHARED_LIBS) {
 284         fprintf(stderr, "BINFMT_FLAT: reference 0x%x to shared library %d\n",
 285                 (unsigned) r, id);
 286         goto failed;
 287     }
 288     if (curid != id) {
 289         if (internalp) {
 290             fprintf(stderr, "BINFMT_FLAT: reloc address 0x%x not "
 291                     "in same module (%d != %d)\n",
 292                     (unsigned) r, curid, id);
 293             goto failed;
 294         } else if ( ! p[id].loaded &&
 295                     load_flat_shared_library(id, p) > (unsigned long) -4096) {
 296             fprintf(stderr, "BINFMT_FLAT: failed to load library %d\n", id);
 297             goto failed;
 298         }
 299         /* Check versioning information (i.e. time stamps) */
 300         if (p[id].build_date && p[curid].build_date
 301             && p[curid].build_date < p[id].build_date) {
 302             fprintf(stderr, "BINFMT_FLAT: library %d is younger than %d\n",
 303                     id, curid);
 304             goto failed;
 305         }
 306     }
 307 #else
 308     id = 0;
 309 #endif
 310
 311     start_brk = p[id].start_brk;
 312     start_data = p[id].start_data;
 313     start_code = p[id].start_code;
 314     text_len = p[id].text_len;
 315
 316     if (!flat_reloc_valid(r, start_brk - start_data + text_len)) {
 317         fprintf(stderr, "BINFMT_FLAT: reloc outside program 0x%x "
 318                 "(0 - 0x%x/0x%x)\n",
 319                (int) r,(int)(start_brk-start_code),(int)text_len);
 320         goto failed;
 321     }
 322
 323     if (r < text_len)                   /* In text segment */
 324         addr = r + start_code;
 325     else                                        /* In data segment */
 326         addr = r - text_len + start_data;
 327
 328     /* Range checked already above so doing the range tests is redundant...*/
 329     return(addr);
 330
 331 failed:
 332     abort();
 333     return RELOC_FAILED;
 334 }
 335
 336 /****************************************************************************/
 337
 338 /* ??? This does not handle endianness correctly.  */
 339 void old_reloc(struct lib_info *libinfo, uint32_t rl)
 340 {
 341 #ifdef DEBUG
 342         char *segment[] = { "TEXT", "DATA", "BSS", "*UNKNOWN*" };
 343 #endif
 344         uint32_t *ptr;
 345         uint32_t offset;
 346         int reloc_type;
 347
 348         offset = rl & 0x3fffffff;
 349         reloc_type = rl >> 30;
 350         /* ??? How to handle this?  */
 351 #if defined(CONFIG_COLDFIRE)
 352         ptr = (uint32_t *) (libinfo->start_code + offset);
 353 #else
 354         ptr = (uint32_t *) (libinfo->start_data + offset);
 355 #endif
 356
 357 #ifdef DEBUG
 358         fprintf(stderr, "Relocation of variable at DATASEG+%x "
 359                 "(address %p, currently %x) into segment %s\n",
 360                 offset, ptr, (int)*ptr, segment[reloc_type]);
 361 #endif
 362
 363         switch (reloc_type) {
 364         case OLD_FLAT_RELOC_TYPE_TEXT:
 365                 *ptr += libinfo->start_code;
 366                 break;
 367         case OLD_FLAT_RELOC_TYPE_DATA:
 368                 *ptr += libinfo->start_data;
 369                 break;
 370         case OLD_FLAT_RELOC_TYPE_BSS:
 371                 *ptr += libinfo->end_data;
 372                 break;
 373         default:
 374                 fprintf(stderr, "BINFMT_FLAT: Unknown relocation type=%x\n",
 375                         reloc_type);
 376                 break;
 377         }
 378         DBG_FLT("Relocation became %x\n", (int)*ptr);
 379 }
 380
 381 /****************************************************************************/
 382
 383 static int load_flat_file(struct linux_binprm * bprm,
 384                 struct lib_info *libinfo, int id, target_ulong *extra_stack)
 385 {
 386     struct flat_hdr * hdr;
 387     target_ulong textpos = 0, datapos = 0, result;
 388     target_ulong realdatastart = 0;
 389     target_ulong text_len, data_len, bss_len, stack_len, flags;
 390     target_ulong memp = 0; /* for finding the brk area */
 391     target_ulong extra;
 392     target_ulong reloc = 0, rp;
 393     int i, rev, relocs = 0;
 394     target_ulong fpos;
 395     target_ulong start_code, end_code;
 396
 397     hdr = ((struct flat_hdr *) bprm->buf);              /* exec-header */
 398
 399     text_len  = ntohl(hdr->data_start);
 400     data_len  = ntohl(hdr->data_end) - ntohl(hdr->data_start);
 401     bss_len   = ntohl(hdr->bss_end) - ntohl(hdr->data_end);
 402     stack_len = ntohl(hdr->stack_size);
 403     if (extra_stack) {
 404         stack_len += *extra_stack;
 405         *extra_stack = stack_len;
 406     }
 407     relocs    = ntohl(hdr->reloc_count);
 408     flags     = ntohl(hdr->flags);
 409     rev       = ntohl(hdr->rev);
 410
 411     DBG_FLT("BINFMT_FLAT: Loading file: %s\n", bprm->filename);
 412
 413     if (rev != FLAT_VERSION && rev != OLD_FLAT_VERSION) {
 414         fprintf(stderr, "BINFMT_FLAT: bad magic/rev (0x%x, need 0x%x)\n",
 415                 rev, (int) FLAT_VERSION);
 416         return -ENOEXEC;
 417     }
 418
 419     /* Don't allow old format executables to use shared libraries */
 420     if (rev == OLD_FLAT_VERSION && id != 0) {
 421         fprintf(stderr, "BINFMT_FLAT: shared libraries are not available\n");
 422         return -ENOEXEC;
 423     }
 424
 425     /*
 426      * fix up the flags for the older format,  there were all kinds
 427      * of endian hacks,  this only works for the simple cases
 428      */
 429     if (rev == OLD_FLAT_VERSION && flat_old_ram_flag(flags))
 430         flags = FLAT_FLAG_RAM;
 431
 432 #ifndef CONFIG_BINFMT_ZFLAT
 433     if (flags & (FLAT_FLAG_GZIP|FLAT_FLAG_GZDATA)) {
 434         fprintf(stderr, "Support for ZFLAT executables is not enabled\n");
 435         return -ENOEXEC;
 436     }
 437 #endif
 438
 439     /*
 440      * calculate the extra space we need to map in
 441      */
 442     extra = relocs * sizeof(target_ulong);
 443     if (extra < bss_len + stack_len)
 444         extra = bss_len + stack_len;
 445
 446     /*
 447      * there are a couple of cases here,  the separate code/data
 448      * case,  and then the fully copied to RAM case which lumps
 449      * it all together.
 450      */
 451     if ((flags & (FLAT_FLAG_RAM|FLAT_FLAG_GZIP)) == 0) {
 452         /*
 453          * this should give us a ROM ptr,  but if it doesn't we don't
 454          * really care
 455          */
 456         DBG_FLT("BINFMT_FLAT: ROM mapping of file (we hope)\n");
 457
 458         textpos = target_mmap(0, text_len, PROT_READ|PROT_EXEC,
 459                               MAP_PRIVATE, bprm->fd, 0);
 460         if (textpos == -1) {
 461             fprintf(stderr, "Unable to mmap process text\n");
 462             return -1;
 463         }
 464
 465         realdatastart = target_mmap(0, data_len + extra +
 466                                     MAX_SHARED_LIBS * sizeof(target_ulong),
 467                                     PROT_READ|PROT_WRITE|PROT_EXEC,
 468                                     MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
 469
 470         if (realdatastart == -1) {
 471             fprintf(stderr, "Unable to allocate RAM for process data\n");
 472             return realdatastart;
 473         }
 474         datapos = realdatastart + MAX_SHARED_LIBS * sizeof(target_ulong);
 475
 476         DBG_FLT("BINFMT_FLAT: Allocated data+bss+stack (%d bytes): %x\n",
 477                         (int)(data_len + bss_len + stack_len), (int)datapos);
 478
 479         fpos = ntohl(hdr->data_start);
 480 #ifdef CONFIG_BINFMT_ZFLAT
 481         if (flags & FLAT_FLAG_GZDATA) {
 482             result = decompress_exec(bprm, fpos, (char *) datapos,
 483                                      data_len + (relocs * sizeof(target_ulong)))
 484         } else
 485 #endif
 486         {
 487             result = target_pread(bprm->fd, datapos,
 488                                   data_len + (relocs * sizeof(target_ulong)),
 489                                   fpos);
 490         }
 491         if (result < 0) {
 492             fprintf(stderr, "Unable to read data+bss\n");
 493             return result;
 494         }
 495
 496         reloc = datapos + (ntohl(hdr->reloc_start) - text_len);
 497         memp = realdatastart;
 498
 499     } else {
 500
 501         textpos = target_mmap(0, text_len + data_len + extra +
 502                               MAX_SHARED_LIBS * sizeof(target_ulong),
 503                               PROT_READ | PROT_EXEC | PROT_WRITE,
 504                               MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
 505         if (textpos == -1 ) {
 506             fprintf(stderr, "Unable to allocate RAM for process text/data\n");
 507             return -1;
 508         }
 509
 510         realdatastart = textpos + ntohl(hdr->data_start);
 511         datapos = realdatastart + MAX_SHARED_LIBS * sizeof(target_ulong);
 512         reloc = (textpos + ntohl(hdr->reloc_start) +
 513                  MAX_SHARED_LIBS * sizeof(target_ulong));
 514         memp = textpos;
 515
 516 #ifdef CONFIG_BINFMT_ZFLAT
 517 #error code needs checking
 518         /*
 519          * load it all in and treat it like a RAM load from now on
 520          */
 521         if (flags & FLAT_FLAG_GZIP) {
 522                 result = decompress_exec(bprm, sizeof (struct flat_hdr),
 523                                  (((char *) textpos) + sizeof (struct flat_hdr)),
 524                                  (text_len + data_len + (relocs * sizeof(unsigned long))
 525                                           - sizeof (struct flat_hdr)),
 526                                  0);
 527                 memmove((void *) datapos, (void *) realdatastart,
 528                                 data_len + (relocs * sizeof(unsigned long)));
 529         } else if (flags & FLAT_FLAG_GZDATA) {
 530                 fpos = 0;
 531                 result = bprm->file->f_op->read(bprm->file,
 532                                 (char *) textpos, text_len, &fpos);
 533                 if (result < (unsigned long) -4096)
 534                         result = decompress_exec(bprm, text_len, (char *) datapos,
 535                                          data_len + (relocs * sizeof(unsigned long)), 0);
 536         }
 537         else
 538 #endif
 539         {
 540             result = target_pread(bprm->fd, textpos,
 541                                   text_len, 0);
 542             if (result >= 0) {
 543                 result = target_pread(bprm->fd, datapos,
 544                     data_len + (relocs * sizeof(target_ulong)),
 545                     ntohl(hdr->data_start));
 546             }
 547         }
 548         if (result < 0) {
 549             fprintf(stderr, "Unable to read code+data+bss\n");
 550             return result;
 551         }
 552     }
 553
 554     DBG_FLT("Mapping is 0x%x, Entry point is 0x%x, data_start is 0x%x\n",
 555             (int)textpos, 0x00ffffff&ntohl(hdr->entry),
 556             ntohl(hdr->data_start));
 557
 558     /* The main program needs a little extra setup in the task structure */
 559     start_code = textpos + sizeof (struct flat_hdr);
 560     end_code = textpos + text_len;
 561
 562     DBG_FLT("%s %s: TEXT=%x-%x DATA=%x-%x BSS=%x-%x\n",
 563             id ? "Lib" : "Load", bprm->filename,
 564             (int) start_code, (int) end_code,
 565             (int) datapos,
 566             (int) (datapos + data_len),
 567             (int) (datapos + data_len),
 568             (int) (((datapos + data_len + bss_len) + 3) & ~3));
 569
 570     text_len -= sizeof(struct flat_hdr); /* the real code len */
 571
 572     /* Store the current module values into the global library structure */
 573     libinfo[id].start_code = start_code;
 574     libinfo[id].start_data = datapos;
 575     libinfo[id].end_data = datapos + data_len;
 576     libinfo[id].start_brk = datapos + data_len + bss_len;
 577     libinfo[id].text_len = text_len;
 578     libinfo[id].loaded = 1;
 579     libinfo[id].entry = (0x00ffffff & ntohl(hdr->entry)) + textpos;
 580     libinfo[id].build_date = ntohl(hdr->build_date);
 581
 582     /*
 583      * We just load the allocations into some temporary memory to
 584      * help simplify all this mumbo jumbo
 585      *
 586      * We've got two different sections of relocation entries.
 587      * The first is the GOT which resides at the begining of the data segment
 588      * and is terminated with a -1.  This one can be relocated in place.
 589      * The second is the extra relocation entries tacked after the image's
 590      * data segment. These require a little more processing as the entry is
 591      * really an offset into the image which contains an offset into the
 592      * image.
 593      */
 594     if (flags & FLAT_FLAG_GOTPIC) {
 595         rp = datapos;
 596         while (1) {
 597             target_ulong addr;
 598             addr = tgetl(rp);
 599             if (addr == -1)
 600                 break;
 601             if (addr) {
 602                 addr = calc_reloc(addr, libinfo, id, 0);
 603                 if (addr == RELOC_FAILED)
 604                     return -ENOEXEC;
 605                 tputl(rp, addr);
 606             }
 607             rp += sizeof(target_ulong);
 608         }
 609     }
 610
 611     /*
 612      * Now run through the relocation entries.
 613      * We've got to be careful here as C++ produces relocatable zero
 614      * entries in the constructor and destructor tables which are then
 615      * tested for being not zero (which will always occur unless we're
 616      * based from address zero).  This causes an endless loop as __start
 617      * is at zero.  The solution used is to not relocate zero addresses.
 618      * This has the negative side effect of not allowing a global data
 619      * reference to be statically initialised to _stext (I've moved
 620      * __start to address 4 so that is okay).
 621      */
 622     if (rev > OLD_FLAT_VERSION) {
 623         for (i = 0; i < relocs; i++) {
 624             target_ulong addr, relval;
 625
 626             /* Get the address of the pointer to be
 627                relocated (of course, the address has to be
 628                relocated first).  */
 629             relval = tgetl(reloc + i * sizeof (target_ulong));
 630             addr = flat_get_relocate_addr(relval);
 631             rp = calc_reloc(addr, libinfo, id, 1);
 632             if (rp == RELOC_FAILED)
 633                 return -ENOEXEC;
 634
 635             /* Get the pointer's value.  */
 636             addr = tgetl(rp);
 637             if (addr != 0) {
 638                 /*
 639                  * Do the relocation.  PIC relocs in the data section are
 640                  * already in target order
 641                  */
 642
 643 #ifndef TARGET_WORDS_BIGENDIAN
 644                 if ((flags & FLAT_FLAG_GOTPIC) == 0)
 645                     addr = bswap32(addr);
 646 #endif
 647                 addr = calc_reloc(addr, libinfo, id, 0);
 648                 if (addr == RELOC_FAILED)
 649                     return -ENOEXEC;
 650
 651                 /* Write back the relocated pointer.  */
 652                 tputl(rp, addr);
 653             }
 654         }
 655     } else {
 656         for (i = 0; i < relocs; i++) {
 657             target_ulong relval;
 658             relval = tgetl(reloc + i * sizeof (target_ulong));
 659             old_reloc(&libinfo[0], relval);
 660         }
 661     }
 662
 663     /* zero the BSS.  */
 664     memset((void*)(datapos + data_len), 0, bss_len);
 665
 666     return 0;
 667 }
 668
 669
 670 /****************************************************************************/
 671 #ifdef CONFIG_BINFMT_SHARED_FLAT
 672
 673 /*
 674  * Load a shared library into memory.  The library gets its own data
 675  * segment (including bss) but not argv/argc/environ.
 676  */
 677
 678 static int load_flat_shared_library(int id, struct lib_info *libs)
 679 {
 680         struct linux_binprm bprm;
 681         int res;
 682         char buf[16];
 683
 684         /* Create the file name */
 685         sprintf(buf, "/lib/lib%d.so", id);
 686
 687         /* Open the file up */
 688         bprm.filename = buf;
 689         bprm.file = open_exec(bprm.filename);
 690         res = PTR_ERR(bprm.file);
 691         if (IS_ERR(bprm.file))
 692                 return res;
 693
 694         res = prepare_binprm(&bprm);
 695
 696         if (res <= (unsigned long)-4096)
 697                 res = load_flat_file(&bprm, libs, id, NULL);
 698         if (bprm.file) {
 699                 allow_write_access(bprm.file);
 700                 fput(bprm.file);
 701                 bprm.file = NULL;
 702         }
 703         return(res);
 704 }
 705
 706 #endif /* CONFIG_BINFMT_SHARED_FLAT */
 707
 708 int load_flt_binary(struct linux_binprm * bprm, struct target_pt_regs * regs,
 709                     struct image_info * info)
 710 {
 711     struct lib_info libinfo[MAX_SHARED_LIBS];
 712     target_ulong p = bprm->p;
 713     target_ulong stack_len;
 714     target_ulong start_addr;
 715     target_ulong sp;
 716     int res;
 717     int i, j;
 718
 719     memset(libinfo, 0, sizeof(libinfo));
 720     /*
 721      * We have to add the size of our arguments to our stack size
 722      * otherwise it's too easy for users to create stack overflows
 723      * by passing in a huge argument list.  And yes,  we have to be
 724      * pedantic and include space for the argv/envp array as it may have
 725      * a lot of entries.
 726      */
 727 #define TOP_OF_ARGS (TARGET_PAGE_SIZE * MAX_ARG_PAGES - sizeof(void *))
 728     stack_len = TOP_OF_ARGS - bprm->p;             /* the strings */
 729     stack_len += (bprm->argc + 1) * 4; /* the argv array */
 730     stack_len += (bprm->envc + 1) * 4; /* the envp array */
 731
 732
 733     res = load_flat_file(bprm, libinfo, 0, &stack_len);
 734     if (res > (unsigned long)-4096)
 735             return res;
 736
 737     /* Update data segment pointers for all libraries */
 738     for (i=0; i<MAX_SHARED_LIBS; i++) {
 739         if (libinfo[i].loaded) {
 740             target_ulong p;
 741             p = libinfo[i].start_data;
 742             for (j=0; j<MAX_SHARED_LIBS; j++) {
 743                 p -= 4;
 744                 tput32(p, libinfo[j].loaded
 745                           ? libinfo[j].start_data
 746                           : UNLOADED_LIB);
 747             }
 748         }
 749     }
 750
 751     p = ((libinfo[0].start_brk + stack_len + 3) & ~3) - 4;
 752     DBG_FLT("p=%x\n", (int)p);
 753
 754     /* Copy argv/envp.  */
 755     p = copy_strings(p, bprm->envc, bprm->envp);
 756     p = copy_strings(p, bprm->argc, bprm->argv);
 757     /* Align stack.  */
 758     sp = p & ~(target_ulong)(sizeof(target_ulong) - 1);
 759     /* Enforce final stack alignment of 16 bytes.  This is sufficient
 760        for all current targets, and excess alignment is harmless.  */
 761     stack_len = bprm->envc + bprm->argc + 2;
 762     stack_len += 3;     /* argc, arvg, argp */
 763     stack_len *= sizeof(target_ulong);
 764     if ((sp + stack_len) & 15)
 765         sp -= 16 - ((sp + stack_len) & 15);
 766     sp = loader_build_argptr(bprm->envc, bprm->argc, sp, p, 1);
 767
 768     /* Fake some return addresses to ensure the call chain will
 769      * initialise library in order for us.  We are required to call
 770      * lib 1 first, then 2, ... and finally the main program (id 0).
 771      */
 772     start_addr = libinfo[0].entry;
 773
 774 #ifdef CONFIG_BINFMT_SHARED_FLAT
 775 #error here
 776     for (i = MAX_SHARED_LIBS-1; i>0; i--) {
 777             if (libinfo[i].loaded) {
 778                     /* Push previos first to call address */
 779                     --sp;       put_user(start_addr, sp);
 780                     start_addr = libinfo[i].entry;
 781             }
 782     }
 783 #endif
 784
 785     /* Stash our initial stack pointer into the mm structure */
 786     info->start_code = libinfo[0].start_code;
 787     info->end_code = libinfo[0].start_code = libinfo[0].text_len;
 788     info->start_data = libinfo[0].start_data;
 789     info->end_data = libinfo[0].end_data;
 790     info->start_brk = libinfo[0].start_brk;
 791     info->start_stack = sp;
 792     info->entry = start_addr;
 793     info->code_offset = info->start_code;
 794     info->data_offset = info->start_data - libinfo[0].text_len;
 795
 796     DBG_FLT("start_thread(entry=0x%x, start_stack=0x%x)\n",
 797             (int)info->entry, (int)info->start_stack);
 798
 799     return 0;
 800 }